Centering-chuck.



vUNITED STATES' rArnNr OFFICE.

ROBERT MILNE, OF ROCKFORD, ILLINOIS, ASSIGNOR TO B. F. BARNES COMPANY, A

i CORPORATION OF ILLINOIS.

GENTERING-CHUCK.

Specification of Letters Patent.

Patented oct. 1s, 190e.

Application led November 21, 1907. Serial No. 4U3,219.

To all whom 'it 'ma/y concern:

Be it known thatI, ROBERTl MILNE, a citiof Illinois, have invented certain new and Fig. 2.

useful Improvements in Centering-Chucks, of which the following is a specification.

The chuck of the present 1nvention is intended more especially for use4 in centering a pulley wheel under the spindle of ar drill; and the object of the invention is to provide means for exactly positioning the pulley wheel and thereafter clamping it during the drilling orv machining operation.

Another object of the invention is to so clamp the pulley wheel or other object that it wi -I'be held against vibration or displacement, and against the tendency to torsional movement due to the revolution of the drill.

A further object. of the invention is to'so construct the clamping jaws that uniform pressure will be applied at all points on tbe circumference of the wheel, whereby a minimum amount of pressure will serve to hold the wheel or other object in clamped ,position.

The `invention consists in the features of construction and combination ofparts hereinafter described and claimed. l

In the drawings, Figure 1 is a perspective view of the entire chuck; Fig. 2 a to or `plan view of the same; Fi 3 a detail o one of the idler ulley whees; and Fig. 4 a cross sectlon view .taken on line 4-4 of The chuck as a wholeis mounted upon a triangular bed plate 5, which isv adapted to be 1positioned and held onv the platen of a dri press or `similar machine, andA the triangular bed plate has mounted thereon three screw-threaded posts or uprights 6, which are positioned at the three corners of the bed late. The screw posts are rigidly entered into the bed, plate and, at their upper ends, are entere through and rigidly secured to a fixed -'awhead 7 having three radially arrange arms 8, the outer ends of which register wi the three corners ofthe triangular bed pla The fixed jaw head copery'ltes with the movable jaw head 9, comprising three arms 1 0 of shape and dimensions simllar g1g-'the radial arms on the fixed j :aw/head, thr gh which arms '9 the screw posts' or uprights are passed. Each of the arms 9 is provided with 'a smooth vertical bore 10* through which is entered a sleeve 11, which upwardly extends from and forms part of a hub 12 integrally formed with an adjusting hand wheel 13: Intermediate the hub and the lower face of the arm is interposed a washer 14 having in its lower face a runway in which are entered balls 14* which provide a suitable bearing for the revolution of the hand wheel.V The hub and sleeve are screw threaded on 4their interior to receive the and the movable jaw head as a whole is adjustable by the hand wheels.v f

Each of the hand wheel has, on its hub, sprocket teeth 15, which are intended 'to engage with an endless chain 16, which runs around the three hand wheels and is ada ted to have its slack adjusted by `means of t ree shafts 1S. The three stub `shafts are adjustably mounted within slots 41,'9 in lugs 20, which outwardly extend from the movable jaw head intermediate the arms thereof. The stub shafts are adapted to be held in adjusted position by means of set screws 21 in wardly extending through the ends of the lugs 20.

Each of thethree arms of the fixed movable-jaw heads is provided, on its inner surface, with teeth 23, which are of wedge shape formation 'havin faces cut at an angle of about 45 andlyingin planes that converge toward-the center of the chuck. `The upper and lower teeth are in exact register wlth one another,the ridges of the up er teeth be ing exactly above and in line wlt the ridges of the lower teeth,V4 and the sides slo mg awa from one another at the same ang c.

T e fixed or upper jaw head is provided, in its exact center, with an opening 24, through which the drill is adapted to enter; and one of the arms is provided with a plurality of radiall arranged holes 25, through .be performed automatically when the jawsscrew threads of the fixed posts or uprights,l

idler pulley wheels 17 journaled upol stub .loo y are adjusted to clam ing position. After the wheel has been lai in lace, as aboveJexplained, one or more of t e hand wheels is revolved, which imparts an equal'revolution to the other hand wheels, whereby the lower f or movable 'jaw will be fed up along the three screw posts as ideways until the uper rimof the positioned ulley wheel is rought into contact with t e jaw teeth on the under face of the xed jaw head. The

lupper teeth, .being in exact register .with the lower teeth, causeethe pulley wheel to automatically move to an exactly' level position and to center itself 'in' the exact center of the chuck. Prior to the final clampin movement, the pin 26 is dropped throug one of i the holes 25, and the wheel is revolved by into contact wlth the pm, after/whic hand sufficiently to bring one ofits s okes the final clamping movement is given. The presence of the pm prevents any turning or torsional movement of the wheel by its contact with one of the spokes, and this obviates the necessity for giving such a tight clamping movement as might be otherwise required.

The device is one which is adapted tou handle pulley wheels of va ing diameter, suHic-ient teeth being rovi ed to accommodate all sizes of whee s withinl a reasonable limit. The idler pulley wheels enable the .endless chain to be adjusted to -any degree of tightness, and the ball bearings serve to minimize friction 1n making the adjustment.

What I regardl as new and desire to sevcure by Letters Patent is:

jaws for centering the work, substantially asl described. j

' 2. In a centering chuck, the combination of a bed plate, threescrew posts entered into the bed plate at points equidistant from one another, a fixed jaw head .into which the upper ends of the screw posts are entered, a movable -jaw head provided" with bores throughA which the screw posts pass, three hubs screw-threaded onto the threads of the screw posts, the upper ends of the hubs being entered through and revoluble within the bores in the movable jaw, sprocket teeth on the three hubs, a hand Wheel on one of the hubs, an endless chain engaging the sprocket teeth, and means on the fixed and movable jaws for centering the work, substantially as described.

3. In a centering chuck, the combination yof a fixed jaw head and a-movable jaw head,

and teeth on the fixed and movable jaw heads, said teeth having slopin flat sides converging towards the center o the chuck, the teeth on the two jaws having their apices in register with one another', and means for adjustin the movable jaw, substantially as described. l"

v4. In a centerin ch ck, the combination of a fixed jaw hea an a movable jaw head,

and sloping surfaces on the two jaws, said surface belng beveled in register with one another 'and sloping in opposite directions, and means for adjusting the movable jaw head, -substantially as described.

5. A centering chuck comprising'a xed jaw head and a movable jaw head, o positel disposed teeth arranged in radial ines on t e two jaw heads and having their apices in alinement with one another and theirv 'sldes' beveled 1n register with one another ROBERT MILNE. Witnesses SAML. H. BECK, W.YB. Bowm. 

